1. Field of the Invention
The present invention relates to an absorbent article such as sanitary napkin, panty liner for absorption of woman's vaginal discharge, incontinence pad, auxiliary absorbent pad for diaper, and disposable diaper, more particularly, relates to an absorbent article in which liquid applied to its skin-side surface can be longitudinally diffused for rapid absorption.
2. Description of the Related Art
Absorbent articles, such as sanitary napkin for absorption of woman's menstrual blood, are typically constructed to include a liquid-impermeable backsheet, an absorbent layer disposed on the backsheet for absorption and retention of liquid, and a liquid-permeable topsheet covering a skin-side surface of the absorbent layer. Liquid discharged from the body may pass through the topsheet mainly in a central portion of the absorbent article for subsequent absorption and retention by the absorbent layer.
In absorbent articles of this kind, it is preferred that the liquid absorption rate is high and the liquid absorption capacity is large, as well as that transverse liquid leakage hardly occurs. Accordingly, the following Patent Publications disclose absorbent articles which are intended to let applied liquid diffuse mainly along a longitudinal direction for effective prevention of transverse liquid leakage.
Patent Publication 1:
    Japanese Unexamined Patent Publication No. H8-511706Patent Publication 2:    Japanese Unexamined Patent Publication No. H2-257951Patent Publication 3:    Japanese Unexamined Patent Publication No.2000-225146
In the absorbent article disclosed in the Patent Publication 1, a liquid orientation component is disposed beneath a topsheet appearing on the skin-side surface. As shown in FIG. 11 of the Patent Publication 1, the liquid orientation component is formed with longitudinal ribs which project toward the skin-side and extend continuously longitudinally in a parallel arrangement. This absorbent article is aimed at guiding liquid, which has passed through the topsheet, in longitudinal movement with the liquid orientation component so as to prevent transverse leakage.
However, since the liquid orientation component is formed of an apertured plastic film and the longitudinal ribs are formed to extend continuously longitudinally, liquid applied to grooves each defined between adjacent longitudinal ribs will take long time to migrate to the absorbent layer, so that the liquid tends to remain in the grooves. Accordingly, this absorbent article presents a problem of delay in the liquid absorption rate.
In FIG. 10 of the Patent Publication 1, there is also disclosed another embodiment of the liquid orientation component being a hydrophobic film structure having a large number of projections, which are of a circular shape as viewed from above, regularly arranged thereon. In this liquid orientation component, however, it is not easy to guide liquid in longitudinal movement, or rather, the projections may possibly block liquid diffusion.
On the other hand, the Patent Publications 2 and 3 disclose a structure in which separate absorbent bodies each extending continuously longitudinally are so disposed that liquid applied to the individual absorbent bodies can be diffused along the longitudinal direction for prevention of transverse liquid diffusion.
In the absorbent articles disclosed in Patent Publications 2 and 3, however, since the separate absorbent bodies are similar in structure, liquid applied to a central absorbent body, for example, may be diffused uniformly in both longitudinal and transverse directions inside the absorbent body. This results in easy migration of liquid to adjacent absorbent bodies, so that when a large amount of liquid is applied, it will be difficult to certainly prevent transverse liquid leakage.